Telephone-transmitter



Patented Feb. 10; 1920.

,Vw p w r 0M 4 Fill A. P. PINKLER. TELEPHONE TRANSMITTER. APPLICATIONFILED MAR. 2, 1911. 1,330,391.

z y rmw .UNITED STATES PATENT orrroE.

ARTHUR P. PINKLER, OF RIDGEFIELD, NEW JERSEY, ASSIGNOR TO WESTERNELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEWYORK.

TELEPHONE-TRANSMITTER.

Specification of Illetters Patent. Patented Feb, 10, 1920. I

Application filed March 2, 1917; Serial No. 151,998.

To all whom it may concern:

Be it known that I, ARTHUR P. PINKLER, a citizen of the United States,residingat Ridgefield, in the county of Bergen and State of New Jersey,have invented certain new and useful Improvements inTelephone-Transmitters, of which the following is a full, clear,concise,and exact description.

This invention relates to telephone transmitters, and in particular itrelates to an improved type of microphonic element or transmitter buttonwherein comminuted material, such as granular carbon, is used as themedium of variable resistance,

Its object is .the construction of the current in the granular materialto a path so located with respect to the fixed and movable electrodes ofthe button that the current therein will be subjected to a maximumvariation, under the influence of electrode motion, without the use ofsmall electrode surfaces and the burning difficulties inherent in suchuse.

To this end, the invention, as applied to the usual cylindrical type oftransmitter button, provides, on the wall of the carbon chamber, aninwardly projecting flange or rib, which, being insulated from thegranular material, constricts the central current path in the button toan opening or channel whose cross-sectional area is less than the areaof either the front or rear electrodes. The invention, therefore, whilepresenting in general the advantages of construction and hightransmittin efliciency of the transmitter of Palmer atent No. 1,132,613,presents an improvement over that construction in that to obtain therequired concentration of the current, it is no-longer necessary toemploy a small electrode surface for the rear or stationary elect de. 4

T e invention will be more clearly understood by reference to theaccompanylng drawings, inwh-ich Figure 1 shows t e transmitter of thisinvention in partia cross-section; and Fig. 2 shows in extended form thegeneral construction of'the transmitter button or microphone element.

Referring to the drawing, 3 is a transmitter casing having a front plate4 threaded to receive the usual transmitter mouthpiece 5. The frontplate 4 also carries the bridge member 6 in which the microphone elementor transmitter button 7 is adjustably supported. A damping spring 8 isalso carried by the bridge 6, and serves to hold the movable electrodemember 9 and the diaphragm 10 against the front plate 4. The dampinspring and diaphragm construction wilfibe more clearly understood byreference to Scribner Patent No. 1,050,304.

Referrin in detail to the construction of the microp one element ortransmitter button which is the subject of this invention, 11 is acup-shaped member having a shank '12 for attachment to the bridge 6 inthe usual'manner. .The member 11 carries the rear or stationaryelectrode 13 of the transmitter, and is threaded to receive a'collar orannular member 14. This member 14 may be of insulating material, or itmay be of metal with the inner surface coated with an insulating japanor other insulating coating. It has an inner annular projection orflange 15, preferably of V -shaped crosssection. The front electrodemember 9 carries the usual flexible annulus 16 of mica or other suitablematerial, and forms the front closure for the button chamber, being heldto the member 14 by the usual threaded ring 17. In the construction asshown the flange 15 is seen to project into the granular mass beyondtheperipheries of both the front and rear electrodes. This has theeffect of increasing the current path between the peripheries of theelectrodes, and there fore serves to eliminate the path of lowresistance and consequent high. current density which obtained in thetransmitter of White Patent No. 485,311. This low resistance path at thebaseof the carbon chamber has been found to have a rather'seriousshunting effect on the active current path in the button, and tointroduce a transmission loss. The present invention, while retainingall of the benefits derived from the large electrode surfaces of theWhite transmitter, restricts the current in the transmitter button tothe central part of the granu: lar mass, thereby eliminating theshunting effect of the low resistance path through the buttonand'connning the current flow to that part of the granular mass which issubjected to the maximum agitationdue to sound waves impinging on thediaphragm 10.

What is claimed is:

. 1. In a, telephone transmitter, an elec-- trode chamber, twoelectrodes spaced apart v Within said chamber, comminuted material Itrally restricted.

v 2. In a telephone transmitter, an electrode chamber, two electrodesspaced apart in said chamber, comminuted material be- 10 tween saidelectrodes, and an annular projection of V-shaped cross-section on theWall of said chamber, and intermediate said electrodes for restrictingthe current flow therebetween to a path Whose central crosssectionalarea is less than the area of either 15 of said electrodes.

In Witness whereof, I hereunto subscribe my'name this 1st day of MarchA. D., 1917.

ARTHUR P. PINKLER.

